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==Paired Helical Filament of tau amyloids found in Down Syndrome individuals==
<StructureSection load='9bxi' size='340' side='right'caption='[[9bxi]], [[Resolution|resolution]] 2.70&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[9bxi]] is a 6 chain structure with sequence from [https://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=9BXI OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=9BXI FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">Electron Microscopy, [[Resolution|Resolution]] 2.7&#8491;</td></tr>
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=9bxi FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=9bxi OCA], [https://pdbe.org/9bxi PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=9bxi RCSB], [https://www.ebi.ac.uk/pdbsum/9bxi PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=9bxi ProSAT]</span></td></tr>
</table>
== Disease ==
[https://www.uniprot.org/uniprot/TAU_HUMAN TAU_HUMAN] Note=In Alzheimer disease, the neuronal cytoskeleton in the brain is progressively disrupted and replaced by tangles of paired helical filaments (PHF) and straight filaments, mainly composed of hyperphosphorylated forms of TAU (PHF-TAU or AD P-TAU). O-GlcNAcylation is greatly reduced in Alzheimer disease brain cerebral cortex leading to an increase in TAU/MAPT phosphorylations.<ref>PMID:19451179</ref> <ref>PMID:2484340</ref> <ref>PMID:14517953</ref>   Defects in MAPT are a cause of frontotemporal dementia (FTD) [MIM:[https://omim.org/entry/600274 600274]; also called frontotemporal dementia (FTD), pallido-ponto-nigral degeneration (PPND) or historically termed Pick complex. This form of frontotemporal dementia is characterized by presenile dementia with behavioral changes, deterioration of cognitive capacities and loss of memory. In some cases, parkinsonian symptoms are prominent. Neuropathological changes include frontotemporal atrophy often associated with atrophy of the basal ganglia, substantia nigra, amygdala. In most cases, protein tau deposits are found in glial cells and/or neurons.<ref>PMID:19451179</ref> <ref>PMID:2484340</ref> <ref>PMID:14517953</ref> <ref>PMID:9629852</ref> <ref>PMID:9736786</ref> <ref>PMID:9641683</ref> <ref>PMID:9789048</ref> <ref>PMID:9973279</ref> <ref>PMID:10553987</ref> <ref>PMID:10214944</ref> <ref>PMID:10374757</ref> <ref>PMID:10489057</ref> <ref>PMID:10208578</ref> <ref>PMID:11117541</ref> <ref>PMID:10802785</ref> <ref>PMID:11071507</ref> <ref>PMID:11585254</ref> <ref>PMID:11278002</ref> <ref>PMID:12473774</ref> <ref>PMID:11921059</ref> <ref>PMID:11906000</ref> <ref>PMID:11889249</ref> <ref>PMID:12509859</ref> <ref>PMID:16240366</ref> <ref>PMID:15883319</ref>   Defects in MAPT are a cause of Pick disease of the brain (PIDB) [MIM:[https://omim.org/entry/172700 172700]. It is a rare form of dementia pathologically defined by severe atrophy, neuronal loss and gliosis. It is characterized by the occurrence of tau-positive inclusions, swollen neurons (Pick cells) and argentophilic neuronal inclusions known as Pick bodies that disproportionally affect the frontal and temporal cortical regions. Clinical features include aphasia, apraxia, confusion, anomia, memory loss and personality deterioration.<ref>PMID:19451179</ref> <ref>PMID:2484340</ref> <ref>PMID:14517953</ref> <ref>PMID:10604746</ref> <ref>PMID:11117542</ref> <ref>PMID:11089577</ref> <ref>PMID:11601501</ref> <ref>PMID:11891833</ref>   Note=Defects in MAPT are a cause of corticobasal degeneration (CBD). It is marked by extrapyramidal signs and apraxia and can be associated with memory loss. Neuropathologic features may overlap Alzheimer disease, progressive supranuclear palsy, and Parkinson disease.<ref>PMID:19451179</ref> <ref>PMID:2484340</ref> <ref>PMID:14517953</ref>   Defects in MAPT are a cause of progressive supranuclear palsy type 1 (PSNP1) [MIM:[https://omim.org/entry/601104 601104]; also abbreviated as PSP and also known as Steele-Richardson-Olszewski syndrome. PSNP1 is characterized by akinetic-rigid syndrome, supranuclear gaze palsy, pyramidal tract dysfunction, pseudobulbar signs and cognitive capacities deterioration. Neurofibrillary tangles and gliosis but no amyloid plaques are found in diseased brains. Most cases appear to be sporadic, with a significant association with a common haplotype including the MAPT gene and the flanking regions. Familial cases show an autosomal dominant pattern of transmission with incomplete penetrance; genetic analysis of a few cases showed the occurrence of tau mutations, including a deletion of Asn-613.<ref>PMID:19451179</ref> <ref>PMID:2484340</ref> <ref>PMID:14517953</ref> <ref>PMID:10534245</ref> <ref>PMID:11220749</ref> <ref>PMID:12325083</ref> <ref>PMID:14991829</ref> <ref>PMID:14991828</ref> <ref>PMID:16157753</ref>   Defects in MAPT are a cause of Parkinson-dementia syndrome (PARDE) [MIM:[https://omim.org/entry/260540 260540]. A syndrome characterized by parkinsonism tremor, rigidity, dementia, ophthalmoparesis and pyramidal signs. Neurofibrillary degeneration occurs in the hippocampus, basal ganglia and brainstem nuclei.<ref>PMID:19451179</ref> <ref>PMID:2484340</ref> <ref>PMID:14517953</ref> 
== Function ==
[https://www.uniprot.org/uniprot/TAU_HUMAN TAU_HUMAN] Promotes microtubule assembly and stability, and might be involved in the establishment and maintenance of neuronal polarity. The C-terminus binds axonal microtubules while the N-terminus binds neural plasma membrane components, suggesting that tau functions as a linker protein between both. Axonal polarity is predetermined by TAU/MAPT localization (in the neuronal cell) in the domain of the cell body defined by the centrosome. The short isoforms allow plasticity of the cytoskeleton whereas the longer isoforms may preferentially play a role in its stabilization.<ref>PMID:21985311</ref> 
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
Down syndrome (DS) is a common genetic condition caused by trisomy of chromosome 21. Among their complex clinical features, including musculoskeletal, neurological, and cardiovascular disabilities, individuals with DS have an increased risk of developing progressive dementia and early-onset Alzheimer's disease (AD). This dementia is attributed to the increased gene dosage of the amyloid-beta (Abeta) precursor protein gene, the formation of self-propagating Abeta and tau prion conformers, and the deposition of neurotoxic Abeta plaques and tau neurofibrillary tangles. Tau amyloid fibrils have previously been established to adopt many distinct conformations across different neurodegenerative conditions. Here, we report the characterization of brain samples from four DS cases spanning 36-63 years of age by spectral confocal imaging with conformation-specific dyes and cryo-electron microscopy (cryo-EM) to determine structures of isolated tau fibrils. High-resolution structures revealed paired helical filament (PHF) and straight filament (SF) conformations of tau that were identical to those determined from AD cases. The PHFs and SFs are made of two C-shaped protofilaments, each containing a cross-beta/beta-helix motif. Similar to filaments from AD cases, most filaments from the DS cases adopted the PHF form, while a minority (approximately 20%) formed SFs. Samples from the youngest individual with no documented dementia had sparse tau deposits. To isolate tau for cryo-EM from this challenging sample we used a novel affinity-grid method involving a graphene oxide surface derivatized with anti-tau antibodies. This method improved isolation and revealed that primarily tau PHFs and a minor population of chronic traumatic encephalopathy type II-like filaments were present in this youngest case. These findings expand the similarities between AD and DS to the molecular level, providing insight into their related pathologies and the potential for targeting common tau filament folds by small-molecule therapeutics and diagnostics.

Cryo-EM structures reveal tau filaments from Down syndrome adopt Alzheimer's disease fold.,Ghosh U, Tse E, Yang H, Shi M, Caro CD, Wang F, Merz GE, Prusiner SB, Southworth DR, Condello C Acta Neuropathol Commun. 2024 Jun 12;12(1):94. doi: 10.1186/s40478-024-01806-y. PMID:38867338<ref>PMID:38867338</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 9bxi" style="background-color:#fffaf0;"></div>
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Homo sapiens]]
[[Category: Large Structures]]
[[Category: Condello C]]
[[Category: Ghosh U]]
[[Category: Southworth D]]
[[Category: Tse E]]